package tmp;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.ScrollBar;
import org.eclipse.swt.widgets.Shell;



public class Snippet9 {

	public static void main (String [] args) {
		Display display = new Display ();
		final Shell shell = new Shell (display, SWT.SHELL_TRIM | SWT.H_SCROLL | SWT.V_SCROLL);
		final Composite composite = new Composite (shell, SWT.BORDER);
		
		composite.setSize (700, 600);
		final Color red = display.getSystemColor (SWT.COLOR_RED);
		composite.addPaintListener (new PaintListener() {
			public void paintControl (PaintEvent e) {
				e.gc.setBackground (red);
				e.gc.fillOval (5, 5, 690, 590);
			}
		});
		final ScrollBar hBar = shell.getHorizontalBar ();
		hBar.addListener (SWT.Selection, new Listener () {
			public void handleEvent (Event e) {
				Point location = composite.getLocation ();
				location.x = -hBar.getSelection ();
				composite.setLocation (location);
			}
		});
		final ScrollBar vBar = shell.getVerticalBar ();
		vBar.addListener (SWT.Selection, new Listener () {
			public void handleEvent (Event e) {
				Point location = composite.getLocation ();
				location.y = -vBar.getSelection ();
				composite.setLocation (location);
			}
		});
		shell.addListener (SWT.Resize,  new Listener () {
			public void handleEvent (Event e) {
				Point size = composite.getSize ();
				Rectangle rect = shell.getClientArea ();
				hBar.setMaximum (size.x);
				vBar.setMaximum (size.y);
				hBar.setThumb (Math.min (size.x, rect.width));
				vBar.setThumb (Math.min (size.y, rect.height));
				int hPage = size.x - rect.width;
				int vPage = size.y - rect.height;
				int hSelection = hBar.getSelection ();
				int vSelection = vBar.getSelection ();
				Point location = composite.getLocation ();
				if (hSelection >= hPage) {
					if (hPage <= 0) hSelection = 0;
					location.x = -hSelection;
				}
				if (vSelection >= vPage) {
					if (vPage <= 0) vSelection = 0;
					location.y = -vSelection;
				}
				composite.setLocation (location);
			}
		});
		shell.open ();
		while (!shell.isDisposed()) {
			if (!display.readAndDispatch ()) display.sleep ();
		}
		display.dispose ();
	}

}
